Donald Trump’s former campaign manager Paul Manafort came under strong pressure from an ex-Russian spy during the presidential campaign to pay his debts to an oligarch, Time revealed. Victor Boyarkin, who was recently put on a sanctions list by the U.S. government, acknowledged to Time that he was in touch with Manafort at the heart of the presidential campaign on behalf of the oligarch. “He owed us a lot of money,” Boyarkin said. “And he was offering ways to pay it back.” Although special counsel Robert Mueller’s office reportedly approached him as part of their investigation, Boyarkin claims he declined to cooperate. But he does appear to be an important link between the Trump campaign and Russian billionaire Oleg Deripaska, a man who is seen as a powerful ally of President Vladimir Putin.

When Manafort joined Trump’s campaign he was almost broke and Deripaska was demanding money from him “over a failed business deal in Ukraine and other ventures,” reports Time. Boyarkin was charged with collecting those debts. “I came down on him hard,” Boyarkin now says. Manafort was in some $17 million in debt.

It had already been reported that Manafort allegedly offered to give Deripaska “private briefings” on the election to “get whole.” But Boyarkin’s name could provide further clues about Manafort’s contacts in Russia and how he is connected to oligarchs who have close ties to the Kremlin. Getting to him was far from easy though. Time explains:

Even after TIME learned his full name in April, he proved a difficult man to find. His online presence amounted to digital scraps: one photo of him at a conference in Moscow, a few benign quotes in the Russian media from his years selling arms for state-linked companies, and some vague references in U.S. government archives to someone by that name, “Commander Viktor A. Boyarkin,” serving in the 1990s as an assistant naval attaché at the Russian embassy in Washington, D.C. – a job sometimes used as cover for intelligence agents.

Only in early October was a TIME reporter able to track Boyarkin down. In the company of a senior Russian diplomat and two young assistants from Moscow, he attended a conference in Greece that was organized by one of Putin’s oldest friends, the former KGB agent and state railway boss Vladimir Yakunin. “How did you find me here,” was the question Boyarkin asked, repeatedly, when confronted about his ties to Manafort during a coffee break at that conference.

Once he agreed to discuss their relationship, it was mostly to confirm the basic facts, often with a curt, “Yes, so what.” (He did not respond to numerous requests for comment after his name appeared on the U.S sanctions list on Dec. 19.)